Ingestible endoscopic optical scanning device

ABSTRACT

An ingestible scanning device includes, in an embodiment, a capsule housing having a transparent window and sized so as to be ingestible, a photo-sensing array located within the capsule housing, a mirror located within the housing and oriented to direct an image from a surface outside the transparent window to the photo-sensing array, and a light source for illuminating the surface outside the transparent window.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of and claims benefit to U.S.patent application Ser. No. 12/370,509, filed Feb. 12, 2009, entitled“INGESTIBLE ENDOSCOPIC OPTICAL SCANNING DEVICE,” which is incorporatedby reference herein in its entirety. The present application also claimsthe benefit of U.S. Provisional Patent Appl. No. 61/028,102, filed Feb.12, 2008, which is incorporated by reference herein in its entirety.

BACKGROUND

1. Field

Embodiments of the present invention relate to optical scanners,specifically optical scanners located on an ingestible endoscopic device

2. Related Art

Modern electronic imaging systems typically utilize a two dimensionalfocal plane array (FPA). However, this requires the use of a singleoptical lens element with a stop that is circularly symmetrical in twodimensions to focus the image onto all of the imaging FPA. Currently,small imaging systems such as those used in camera pills for biomedicalcameras, as well as for security and industrial applications, arelimited in resolution by the pixels in their FPA chip. As a result, thecurrent camera pills for gastric intestinal (also referred to herein asendoscopic) examination have a relatively low resolution of, forexample, 300×300 pixels. This results in images that provide extremelylimited details and cannot be enlarged significantly for improveddiagnostic analysis.

These systems are further impaired with the orientation of the arraysuch that the field of view of the camera pill is continuous and fixed.For example, a camera pill may only look down the central axis of thepill and GI tract thereby presenting the center of the field of view ashaving very little to no useful image data. Additionally, these camerapills typically require extremely wide angle “fish-eye” lenses to imagethe tissue along the intestinal wall with the result that the images aredistorted and non-uniformly illuminated.

Further, use of a fish-eye lens generates images where the informationof the condition of the inside wall of the GI tract is only contained ina ring of pixels at the peripheral region of the image. In thissituation the center region of the image shows a view down the length ofthe intestine and contains little or no useful information. This resultsin images where the most important data is presented on a small fractionof the pixels in a focal plane imaging array such as a CCD or CMOSimager. This reduction in the effective resolution is exacerbated by thepresentation of the image in a distorted circular appearance with themost outer edge visible being brightly lit and close to the imagingarray while the rest of the intestinal wall surface is progressivelyfurther away from the camera and progressively dimmer in illumination.

Additionally, the images of interest to a physician are images of theintestinal wall, not the forward-looking view down the GI tract. Theability to scan the intestinal walls is thus preferred over traditionalcamera pill imaging. The ability for the capsule to image the entiretubular wall and the size and electrical connections required for thefocal plane array define that the image array be set so that the imagingsurface is perpendicular to the axis of the pill.

SUMMARY

An ingestible scanning device includes, in an embodiment, a capsulehousing having a transparent window and sized so as to be ingestible, aphoto-sensing array located within the capsule housing, a mirror locatedwithin the housing and oriented to direct an image from a surfaceoutside the transparent window to the photo-sensing array, and a lightsource for illuminating the surface outside the transparent window.

Further features and advantages of the invention, as well as thestructure and operation of various embodiments of the invention, aredescribed in detail below with reference to the accompanying drawings.It is noted that the invention is not limited to the specificembodiments described herein. Such embodiments are presented herein forillustrative purposes only. Additional embodiments will be apparent topersons skilled in the relevant art(s) based on the teachings containedherein.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate the present invention and, togetherwith the description, further serve to explain the principles of theinvention and to enable a person skilled in the relevant art(s) to makeand use the invention.

FIG. 1 illustrates an ingestible scanner according to an embodiment ofthe present invention.

FIGS. 2A and 2B illustrate a lighting system for use in an ingestiblescanner, according to an embodiment of the present invention.

FIG. 3 illustrates an exemplary endcap of an ingestible scanner,according to an embodiment of the present invention.

FIG. 4 illustrates additional exemplary endcaps of an ingestiblescanner, according to an embodiment of the present invention.

FIG. 5 illustrates a cross-section of an ingestible scanner according toan embodiment of the present invention.

FIG. 6 illustrates a cross-section of another ingestible scanneraccording to an embodiment of the present invention.

FIG. 7 illustrates a cross-section of another ingestible scanneraccording to an embodiment of the present invention.

FIG. 8 illustrates exemplary scribes used in an embodiment of thepresent invention.

FIG. 9A is a cross-section of a photodiode.

FIG. 9B is a top-down view of the photodiode of FIG. 9A.

FIGS. 10A and 10B illustrate construction of a back-lit scanneraccording to an embodiment of the present invention.

FIG. 10C is a top-down view of a photosensor array using the scanner ofFIGS. 10A and 10B.

FIG. 11 illustrates an exemplary reflective element according to anembodiment of the present invention.

FIG. 12 illustrates another exemplary reflective element according to anembodiment of the present invention.

FIG. 13 illustrates an exemplary reflective and refractive elementaccording to an embodiment of the present invention.

The features and advantages of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

DETAILED DESCRIPTION

While specific configurations and arrangements are discussed, it shouldbe understood that this is done for illustrative purposes only. A personskilled in the pertinent art will recognize that other configurationsand arrangements can be used without departing from the spirit and scopeof the present invention. It will be apparent to a person skilled in thepertinent art that this invention can also be employed in a variety ofother applications.

It is noted that references in the specification to “one embodiment”,“an embodiment”, “an example embodiment”, etc., indicate that theembodiment described may include a particular feature, structure, orcharacteristic, but every embodiment may not necessarily include theparticular feature, structure, or characteristic. Moreover, such phrasesare not necessarily referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with an embodiment, it would be within the knowledge of oneskilled in the art to effect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

An ingestible sensor device may be swallowed by a patient, such as ahuman, to diagnose one or more conditions of the patient. The ingestiblesensor device may include a sensor configured to receive a stimulusinside the gastrointestinal tract of the patient, wherein the sensor isconfigured to output a signal having a characteristic proportional tothe received stimulus. The ingestible sensor device may further includea communications module that transmits an acoustic signal modulated withthe sensor output signal and a housing configured to have a size that isswallowable, wherein the housing substantially encloses the sensor andcommunications module. The patient using the ingestible sensor devicesmay be any type of animal, including a human. In addition, these samesensor devices may be temporarily implanted into patient for the purposeof continuous monitoring, such as with a several hour to several daydiagnostic period at ‘home’ or at a professional care center. A sensorlink module may be located on the surface of the patient to receive theacoustic signal output by the sensor. An example ingestible sensor isfurther described in U.S. patent application Ser. No. 11/851,221, filedSep. 6, 2007, and U.S. patent application Ser. No. 11/851,214, filedSep. 6, 2007, each of which is incorporated by reference herein in itsentirety.

An ingestible sensor device may benefit from an optical scanner coupledto the ingestible sensor device. Although the present invention will bedescribed with respect to an ingestible endoscopic sensor device, one ofskill in the art will recognize that an optical scanner as describedherein may be coupled to any type of ingestible device, or may be usedon its own, without departing from the spirit and scope of the presentinvention. Scanned image data from the ingestible sensor device may betransmitted outside the body through use of acoustic data transmission,or using any other type of data transmission known to one of skill inthe art. Additional embodiments and features of a radial scanner thatmay be used in conjunction with the present invention are described inU.S. Prov. Patent Appl. No. 61/030,453, filed Feb. 21, 2008, which ishereby incorporated by reference in its entirety. Additionally, althoughthe present invention is described in conjunction with scanning insidethe gastrointestinal tract, one of skill in the art will recognize thata similar scanner may also be used inside vasculature, urinary tract,reproductive tract, lung, nasal or internal ear cavity, or any othercavity of an animal as also described in U.S. Prov. Patent Appl. No.61/030,453.

Unlike typical camera pills, in an ingestible endoscopic scanner, theneed for a focal plane to generate a two dimensional image can beeliminated by the use of a single axis or single element photo-sensorthat is coupled with an optical scanning element or is physicallyscanned over the desired field of view. Whereas the image taken by afocal plane array is simultaneous over the entire field of view and mustbe scanned out to a memory for transmission, the single axis sensingarray is capable of being read a line at a time. With the combination ofa scanner, a broadband source, and a linear array, a point-by-pointspectrum can be produced using diffractive optics.

The scan line images may be generated without the two dimensionalcircular lens and stop element used in existing ingestible cameras. Inthis manner, the single line array of pixels can scan a region such thatin one axis, the linear line array provides the resolution while in theopposing axis a scanning system is utilized. In this manner, as will bedescribed further below, the scanning element can be composed of any ofa variety of opto-mechanical configurations composed of, for example, anoscillating mirror, a prism, a cylindrical lens, etc. This allows theachievable resolution of the scanned axis and the speed of imaging to beadjustable. Also, this scanning approach can be used with illuminationor in combination with a joint illumination and imaging opticalconfiguration producing a highly efficient optical imaging system. Inembodiments, this construction may lead to the pixel area on the surfacebeing imaged being defined by the spot size generated by the lightsource. Color images can be generated either by sequential scans withswitching color light sources, or by using pixel rows on thephoto-sensor array each with a color filter assigned to each row.

FIG. 1 illustrates an exemplary ingestible scanner 100 according to anembodiment of the present invention. A single axis photo-sensing array102 is located such that it extends across the diameter of a capsulehousing 104 and is perpendicular to the axis of the capsule and the axisof housing 104. Array 102 may be, for example and without limitation, asingle photosensing diode (also referred to herein as a photosensor orphotodetector) or a one-dimensional array of multiple photosensors.Housing 104 may be, for example, a tubular housing. A mirror 106 withinthe pill is placed such that it is at an angle to array 102 that allowsarray 102 to view the intestinal wall surface 108 through the side wallof housing 104 through a clear aperture 110 in housing 104. Mirror 106may be, for example, an elliptical mirror. Alternatively, mirror 106 maybe a rectangular mirror that deflects on only one axis. Mirror 106 maybe placed at an angle of, for example, 90 degrees to array 102. Mirror106 may be a two-sided mirror, to capture twice the data in a singlerevolution. Aperture 110 may extend for 360 degrees around housing 104.Mirror 106 may be coupled to a micro-motor 112 such that an electricalsignal causes mirror 106 to rotate. The axis of rotation of mirror 106is approximately parallel to the axis of capsule 100. The rotation ofmirror 106 results in array 102 scanning, in a 360 degree field, theregion surrounding capsule 100. In an alternative embodiment (notshown), mirror 106 may be attached to a rod having two conductors andsuspended in an electrical coil, such that the rod rotates aselectricity is applied to the coil.

In an embodiment, a cylindrical lens 114 is placed over array 102 tofocus light from surface 108 reflected by mirror 106 onto array 102.Because array 102 is imaging surface 108 through aperture 110 on theside of capsule 100, rather than through the end of capsule 100,resolution of array 102 is approximately uniform at any given scan rate.Resolution may be increased in the rotational axis by adjusting thespeed of rotation of mirror 106.

Array 102 is used to generate one or more images of surface 108 byscanning. This is accomplished in one embodiment by moving cylindricallens 114, which is placed down the length of array 102 such that thecurvature of cylindrical lens 114 is perpendicular to the length ofarray 102. Scanning of the region to be imaged (such as surface 108) isachieved by movement of the relative position of cylindrical lens 114 toarray 102. In an embodiment, either of array 102 or cylindrical lens 114can be moved. In this manner, light from different regions of the imageare focused sequentially onto the pixels of array 102 as the movementoccurs. By use of cylindrical lens 114 (or a more complex lens surface,in an embodiment) extremely wide angle images can be achieved on theaxis of the image that is scanned.

In an embodiment, cylindrical lens 114 is replaced with a scanningmirror or prism. The prism may have either a transmissive or reflectivefunction depending upon the scanning optical design.

Illumination of the imaged wall region, such as surface 108, may beaccomplished by placing LED light sources adjacent to array 102, tocreate a light distribution ring, or “light pipe” 116. In an embodiment,light pipe 116 evenly outputs light around approximately the entireperimeter of housing 104. In an embodiment, light from light pipe 116 isoutput at multiple frequencies. In this manner individual scans orframes of different frequencies can be captured and integrated into fullcolor images, partial color images or false color images. Light sourcesmay include, for example and without limitation, narrow band emitters inthe visible range, white light emitters, ultraviolet emitters andinfrared or near infrared emitters. Imaging arrays comprising, forexample, three rows of photo-sensors, each with a specific color filter,may be used to generate full visible color images. In this manner theimaging system can be utilized to detect reflection differences intissue over a spectral range far exceeding the abilities of the humaneye. In an embodiment, a pixel size of array 102 may be controlledthrough the use of mechanical shutters or a shutter wheel. The shutterwheel may include one or more color filters.

In an embodiment, light pipe 116 is located within housing 104. Inanother embodiment, light pipe 116 is external to housing 104. In anembodiment where light pipe 116 is located external to housing 104,light pipe 116 acts to space the scanning optics off the intestinalwall. Further, positioning light pipe 116 outside housing 104 ensuresthat the light source path is separated from the received light path,with no internal reflecting surfaces.

In one embodiment, the entire light pipe 116 may be illuminated at agiven time, providing illumination for the entire circumference of theintestinal wall at the same time. In another embodiment, in order topreserve power, light pipe 116 may direct light only to the portion ofsurface 108 being imaged at a given time by array 102. FIGS. 2A and 2Billustrate an exemplary lighting system for focusing illumination lighton intestinal wall surface 108. FIG. 2A illustrates a cross-sectionalview of the directional lighting system. As shown in FIG. 2A, a toroidallens 202 surrounds array 102. The relationship between toroidal lens 202and array 102 is further illustrated in FIG. 2B. Returning to FIG. 2A,toroidal lens 202 directs illumination light from light source 204(which may be, for example, an LED) to mirror 106. Mirror 106 furtherfocuses the illumination light onto surface 108. Mirror 106 may bepositioned such that surface 108 is approximately located at a focalpoint of mirror 106. Alternatively, a collimating lens (not shown) maybe included between surface 108 and mirror 106 to account for any focallength variability of surface 108. An image from surface 108 is thenreturned to array 102.

Alternatively, illumination may be provided to a small portion ofsurface 108 using an optical fiber to direct the illumination lightaccordingly. In yet another alternative, a photosensor in array 102 mayinclude a hole that allows light to pass through array 102 to mirror106, and then be reflected onto surface 108.

Illuminating only a small portion of the surface preserves power in theingestible capsule, because light produced by the light source isfocused onto a specific spot rather than distributed across many spots.This allows the amount of radiation output by the light source to bedecreased without changing the radiation per pixel received.

Illuminating a small portion of a surface also allows image processingof the imaged surface such that very accurate colorimetry measurementsmay be made, according to an embodiment of the present invention. Colorinformation may be obtained through use of an array having more than onephotodetector element, such as a two- or four-element array. In oneembodiment, the array may be separated into subcategories of traditionalred, blue, and/or green. Alternatively, a single photodetector elementmay be used with multiple color light emitting diodes (LEDs), as use ofa single photodetector element maximizes the sensitivity of the aperturesize. This allows inspection of tissue for regions which have a slightloss of oxygen or are just becoming infected or inflamed. This techniqueprovides higher accuracy of these conditions than that capable withwhite light and the human eye.

In an embodiment, the illumination intensity can be varied for differentviews. For example, illumination intensity may be increased whenscanning points of particular interest, such as a surface of theintestinal wall. Similarly, illumination intensity may be decreased whenscanning across points of lesser interest, such as down the intestinewhere less light will be reflected back to the detector.

Returning to FIG. 1, the scan rate, as determined by the rotational rateof mirror 106, may be adjusted to match a desired frame rate. Thisrequires less memory and allows more flexibility of the imaging rate.The ability to scan the image with an optical mechanical device alsoallows the elimination of a complex lens. Although FIG. 1 illustratesmirror 106 as coupled to motor 112 for rotating mirror 106, scanning canalternatively or additionally be accomplished by moving array 102,tilting mirror 106 to view 360 degrees around the sides of capsule 100,or by moving cylindrical lens 114 to scan a region. The rate of motionof array 102, mirror 106, or lens 114 defines the rate of the scan inone axis. For example, mirror 106 may not only be rotatable around acapsule axis 118, but it may also be tiltable, having a pivot lineperpendicular to axis 118. Such a tiltable, rotatable mirror provides atwo-axis range of motion of mirror 106.

In an embodiment, light pipe 116 homogenizes the intensity and convertsthe light into a ring which illuminates the optical scanning region witha highly uniform ring of light. In a specific example, not intended tolimit the present invention, mirror 106 is oriented at 45 degrees withrespect to array 102. Motor 112 rotates mirror 106 and a lens is placedso that array 102 images a 0.5 degree instantaneous field of view. Thestart of each scan line may be identified by the use of an occlusion inthe field of view, such as wires attaching array 102 to its supportingelectronics. In this specific example, the system provides approximately720 pixels per scan with a pixel size of 55 microns. In this example,data may be captured at 16 bits per color giving a 48 bit full colordata per pixel. In this example, scan rates may vary from, for example,1000 rpm to 10,000 rpm. This provides an example resolution of 720×405pixel full color image comprising 875,000 pixels, which is approximately⅓ the resolution of a high-definition television. In another example,the axial scan may include a full 720 pixel resolution of 720×1280pixels.

In an embodiment, the scanner may use feedback from other sensors in thecapsule to enter into a single color mode when a full color scan is notsubstantially different from a previous scan. Similarly, the scanner mayenter into a multi-color mode (using two or more colors) when a singlecolor scan is different from previous scans. In another embodiment, suchcolor selection instructions may be received from an operator externalto the capsule instead of other sensors within the capsule.

Various additional embodiments are possible using tilting and/orrotating mirrors and/or arrays. As shown in FIG. 1, a second opticalsystem may be located on the opposite end of capsule 100 from array 102and mirror 106. This allows a 360 degree field of view for capsule 100.FIGS. 3-7 each illustrate a different exemplary configuration forcapsule 100.

In FIG. 3, the end of capsule 300 containing the imaging optics includesa globe-shaped housing 302. This allows a very wide angle field to beimaged by photodetector 304.

In FIG. 4, ends 402 a and 402 b of capsule 400 are shaped like atruncated cone, so that light enters the imaging optics through a flatsurface. This increases the simplicity of optics required to counteractdistortion caused by light passing through housing 404.

FIG. 5 illustrates a cross-section of a capsule 500, wherein the imagingoptics are not located at the ends of the capsule, but instead arelocated in the central portion of the capsule. Mirror 502 is located ona central cylinder 504. At least a portion of housing 506 istransparent, such that an image from intestinal wall surface 508 isreflected by mirror 502 to photodetector 510. Central cylinder 504 maybe rotatable, such that mirror 502 can image around the full perimeterof capsule 500. In an embodiment, mirror 502 is a dish mirror to directlight to photodetector 510 when mirror 502 is tilted. In an embodiment,central cylinder 504 includes an illuminator. The illuminator may belocated inside central cylinder 504 with light exiting through a slit incentral cylinder 504 (not shown) in order to illuminate intestinal wallsurface 508.

FIG. 6 illustrates a cross-section of a capsule 600, wherein the imagingoptics are located in the central portion of the capsule. In thisembodiment, photodetector 602 is located on a central cylinder 604.Central cylinder 604 may be made from a reflective material, such thatan image from intestinal wall surface 610 enters through transparenthousing 606 and reflects off central cylinder 604 to a mirror 608. Theimage is further reflected by mirror 608 to photodetector 602. Centralcylinder 604 may be rotatable, such that photodetector 602 can imagearound the full perimeter of capsule 600.

FIG. 7 illustrates a cross-section of a capsule 700, wherein the imagingoptics are surrounded by hemispherical lenses 702 a and 702 b on eitherend of capsule 700. In an embodiment, hemispherical lenses 702 a and 702b may be organized in conjunction with a pre-distorted lens to scan arespective hemisphere of the GI tract with high resolution on the sidewalls and graduated lower resolution toward the centerline of thescanner field of view.

In an embodiment where a 2 dimensional photodetector array is used, aconical reflector 1102 may be oriented along the center axis of theoptical lens system, as illustrated in FIG. 11. In a similar embodiment,a parabolic mirror or other cylindrically symmetrical reflector, asillustrated in FIG. 12, may be used in place of the conical reflector.In still another embodiment, this mirror element may be composed of oneor more reflective and refractive surfaces, as illustrated in FIG. 13.An image may be taken of the inside of the GI tract that maximizes thenumber of pixels in an imaging array that present a useful image of theinternal wall. In addition, illumination of the wall perpendicular tothe orientation of the scanner presents a field of view with the tissuesat nearly a constant distance from the scanner lens. This improves theability to capture scan images at a uniform focus, resolution andillumination intensity.

In this embodiment, the conical reflector is designed to match the fieldof view of the lens and deflect the image into a circular band that iscentered at or near 90 degrees to the original axis of the lens. In thismanner the lens is provided with an image region where optical pathlengths from one edge of the cylindrically imaged region areapproximately equidistant to the path length of the opposing edge of theimaged region. A moderate field of view may thus be obtained with anormal lens. This allows simple optical elements to be used with minimalfocal or distortion issues. Nearly all the pixels within the imagingarray are presented with useful information. This maximizes the usableresolution in the resulting image. It is also easier to illuminate theimaged region in a near uniform manner. The images may then be processedto remove the circular distortion and produce panoramic images thatrepresent an unwrapped and undistorted image of the interior wall.

Another embodiment whereby effects of a variable focal distance aremitigated includes changing the focus position of the lens to bring anyspecific distance of the imaged surface into focus. Oscillating thefocus from a close position to a distant position creates a temporallyfocused image. This approach can then be used to determine the distancebetween any region of the imaged surface and the lens. By furtherincorporating software that can selectively capture regions of the imagewhen they are in focus, it is possible to generate a composite imagewhere the entire image is in focus or to generate a depth map of thesurface. Once a depth map of the surface is created, additional imageprocessing can provide a parallax calculation to be made, and images canthereby be created which represent the surface in three dimensions.

More particularly, the distance between the imaging lens and the film orimage sensing array (such as a CCD or CMOS focal plane array) may varydepending upon the distance at which the imaged surface is in focus.This results in the spacing of the lens varying as various distances ofthe imaged surface are brought into focus. By smoothly oscillating thelens between its minimal and maximum spacing above the film or imagingarray, it is possible to generate a series of images or frames whereeach surface region is progressively brought into focus from the closestto the farthest from the lens. Sharp objects or markings on the surfaceswhich represent high contrast regions (such as edges of shadows or sharpedged color differences) are sharp and high contrast only when they arein focus. The contrast of these objects drops rapidly when the lensposition is changed even slightly. In this manner, it is possible toutilize software that analyzes pixel values and identifies adjacentpixels having sharp intensity variations when the lens is in otherspacing positions. By capturing these regions in a sequential manner, itis possible to generate a composite image where the entire image surfaceis presented in sharp focus. The lens spacing information correspondingto each image may be used to create a depth profile map of the surface.This profile may then be used to generate a pseudo three dimensionalimage by generation of images representative of a parallax pair ofimages, where the position of near field surfaces is shifted more thanthe background surfaces.

By utilizing image processing algorithms that capture regions of animage at their highest contrast and incorporating a rapidly dynamicfocusing lens system that has a narrow depth of field, the focusposition may be used to generate a depth profile of the image. Thisdepth profile may then be utilized to generate a topographic map of theimaged region. The depth profile can additionally be utilized togenerate a pseudo-parallax perspective of the imaged region and presentthe processed image in three dimensions utilizing head-mountedstereoscopic displays or other similar devices. In addition, distortionsto the image may be created to enhance the representation of depth on asingle display monitor.

This allows presentation of a fully focused image of tissues which varygreatly in distance from the imaging lens, while utilizing an opticallens system designed for the highest light efficiency possible. Inaddition, the ability to generate depth profiles and pseudo threedimensional images can assist a physician in visualizing the relativeposition of the tissues, further assisting in diagnosis.

In another embodiment, a scanner having multiple photodetectors in itsarray enables not only spot detection but also the level of lightdiffused from the coherent signal sent out. The diffusion may beimportant, because rough tissue scatters light much more than smoothtissue. Having multiple photodetectors in the array not only offers again advantage in that it is more sensitive to reflected light, but italso offers an opportunity to determine a relative amount of light inthe center of the image versus the outside of the image, and gives anapproximate correlation to smooth tissue as opposed to rough tissue.

As has been discussed, an ingestible optical scanner may include atiltable and/or rotatable mirror for capturing a wide angle field ofview. In an embodiment of the present invention, as introduced withrespect to FIG. 1, a capsule may contain two scanning systems, one oneach end of the capsule. As discussed above, FIG. 7 is an illustrationof an exemplary capsule 700 having scanning optics located in twohemispherical lenses 702 a and 702 b. Depending on the field of view, itmay be possible for each scanning system 702 a and 702 b to image thesame feature 704 on an intestinal wall surface 706. Because of theeffects of parallax caused by the distance d separating optics 708 a and708 b, a three-dimensional image of feature 704 may be obtained.Although this three-dimensional feature is described with respect tohemispherical lenses 702 a and 702 b, one of skill in the art willrecognize that any type of lenses may be used without departing from thespirit and scope of the present invention.

In another embodiment, a single scanning system may image a feature suchas feature 704 from two different locations within the GI tract. In thisembodiment, parallax due to the distance between the two locations maybe used to provide a three-dimensional image of the feature.

In an embodiment of the present invention, the mirror used to reflectimages to the capsule's imaging sensor may have scribes located on themirror's surface in predetermined equal distances from each other. Anexample set of scribes is illustrated in FIG. 8. Although FIG. 8illustrates the distance between scribes in terms of micrometers, thedistance between scribes could alternatively be fractions of mm,fractions of an inch etc. This provides accurate reference dimensions toaid a physician in identifying size of objects in view on the picture.The scribes on the mirror may result in pictures having the scribe linesalways showing as a reference on each and every frame.

The mirror may also be a magnifying mirror, where the magnification is,for example and without limitation, 2×, 3×, or 4× as desired for a givenpurpose. This enhances the scanning capsule endoscope by increasingresolution using optical magnification. When the scribes are designedfor the magnifying mirror, the magnification should be appropriatelyconsidered.

2. Variable Resolution and/or Variable Magnification Scanning

In an embodiment, the resolution of an axis can be controlled by thescanning optical system. This allows for higher resolution images to begenerated than with existing FPA chips within the size range required ofthe applications. In addition, for many applications, the imaging rate(frame rate) and resolution of the images does not need to be at a fixed(e.g., video) rate. This allows the scan system to operate at variablespeeds such that when triggers within the image are activated, from, forexample, additional sensors within the capsule or from an operatorexternal to the capsule, the speed of the image generation can bechanged. For example, the data rate generated can be lowered wheninformation is redundant or not of interest, and increased when specificimage information is critical to the application or different from aprevious scan. This increases the efficiency of the informationgathering and is similar in result to image compression. In anotherexample, a low resolution scan may be taken when the ingestible capsuleis moving through the GI tract, to ensure that information regarding theportion of the GI tract through which the capsule is passing isobtained. When the capsule is not moving, the resolution can be rampedup to obtain higher resolution images of the location. In yet anotherexample, each color may be imaged in either high resolution or lowresolution depending on a previous scan and a threshold of differencefrom the previous scan.

Under the variable resolution scanning approach, a slower scan can beused to produce a higher resolution image on the scanning axis. The useof a cylindrical lens (such as cylindrical lens 114) or other scanningmirror and/or prism optics provides wide angle imaging withoutdistortion and without requiring complex optical surfaces. A radialresolution of the capsule is a function of the scan rotation rate, andis approximately equal to the line scan capture rate divided by thenumber of rotations per second of the scanning optics. To obtain a highresolution, for example, the capsule may capture a line scan image everydegree around the viewing field. One of skill in the art will recognizethat other rates of line scan image capture may be utilized withoutdeparting from the spirit and scope of the present invention. A lengthresolution of the capsule is a function of the linear velocity of thecapsule (such as the rate at which the capsule moves through the GItract), and is approximately equal to the number of rotations per secondof the scanning optics divided by the linear velocity.

By using discrete frequency illumination, each scan can be used tocollect the different reflectivity of the target surface, and thereforecan be used to generate full color images and spectral analysis data atvarious resolutions.

Such a technique may also be used to vary the magnification of an imagewithout any modifications to the detector. That is, if the spot sizedecreases while resolution stays constant, an increase in magnificationresults.

3. Photosensor Construction and Image Data Format

The top surface of a typical integrated circuit, including a focal planeimage sensor, has nearly complete metal coverage. This metal is requiredto provide addressing, data readout, as well as cell, or pixel,transistor circuit connections. Each pixel's photodiode (that is, lightsensor) must be placed in an area where incoming light can reach it.FIG. 9A is an illustration of a cross-section of a typical photodiode. Aphotosensor 902 is implemented in CMOS. As the supporting electronicsare designed depending on the characteristics of photosensor 902, theyare implemented on the chip after the implementation of photosensor 902.Supporting electronics for photosensor 902 are illustrated aselectronics 904. Incoming light beam 906 enters through a hole inelectronics 904 so as to be incident on photosensor 902. Because of thespace needed for electronics 904, the majority of the pixel area underelectronics 904 cannot be used for light sensing. This limits theavailable light sensitivity as well as the resolution of photosensor902. Dark current and coupled noise further limits the sensitivity ofthe photosensor 902. This disparity between the size of photosensor 902and the size of a pixel containing photosensor 902 is illustrated inFIG. 9B, which is a top-down view of a portion of an exemplaryphotosensor array.

Large image sensors for a given pixel density have been used to provideimage resolution and light sensitivity. However, the dark current andcoupled noise is a tradeoff limitation of current image sensors.Additionally, this results in a significant amount of illumination thatmust be supplied by LED light sources on the pill, and thus a portion ofthe pill's battery capacity is required for it.

In an embodiment, a Silicon-on-Insulator (SOI) CMOS image scanner may beilluminated from the back of the integrated circuit to achieve a maximumlight sensitivity and finest image resolution, while enabling a smallimage scanner integrated circuit. FIGS. 10A and 10B illustrate how sucha back-lit scanner may be constructed. As shown in FIG. 10A, a base 1002of silicon oxide (SiO₂) is implemented in place of traditional CMOS. Asacrificial metal layer 1004 is also included to provide support forbase 1002. Photosensor 1006 and supporting electronics 1008 areimplemented as usual, with no hole being included in electronics 1008for accessing photosensor 1006.

As shown in FIG. 10B, once sacrificial layer 1004 is removed, a lightbeam 1010 may be incident on photosensor 1006 through transparent base1002. Because the size of photosensor 1006 is no longer limited by thearea requirements for supporting electronics 1008, photosensor 1006 canbe made larger, as illustrated in FIG. 10C, which is a top-down view ofan exemplary photosensor array. Indeed, photosensor 1006 can be madelarge enough to have double digit electron sensitivity or less.

This integrated circuit technology makes it possible to capture highresolution peripheral scanned images through hemispherical optics withlower image data along the center line of the optics, in accordance withan embodiment of the present invention. On-chip image scanner circuitrymay also be incorporated with variable resolution in an embodiment ofthe present invention to trade-off resolution with the quantity of dataunder electronic control.

In an embodiment, optimized circuit design and layout is performed indefining the electronic arrangement of the pixel circuitry and pixelphoto sensor diodes. The photosensor diodes may be substantiallyarranged in a circular pattern for scanning the illuminatedhemispherical field of view. The hemispherical optics (such as a fisheyelens or cylindrical lens) may work in conjunction with the image scannerlayout. This arrangement offers scanning information capture and outputof the image in a radial data format. In an embodiment, the outerperiphery of the scanning radius contains a higher density of pixelsthan the center, which has the lowest pixel count per unit area ofsilicon by simple geometry. This provides the highest resolution on thesidewall of the intestine at or near the endoscopic capsule, while lowerresolution is provided down the intestinal tract. The read-outelectronics may be located primarily in the center of the array wherethe readout lines are the shortest for low power operation. A lowdensity of pixels may be located throughout the readout electronicregion for coverage in the center of the hemispherical scanned imagewhich looks down the intestinal tract. The four corners may also usedfor image electronics, since there are no pixels located there.

In an embodiment, three dimensional data is derived by combiningmultiple images, especially those that form opposite ends of thecapsule. Post-processing of this combined data may be performed forareas of interest by the physician's desk. Once an area of interest isselected, the data may be processed and viewed at the operator'scommand. Three dimensional viewing modes may be similar to fly-over mapviewing having controls for elevation and azimuth.

Further regarding this embodiment, the primary data format has 0 to 360degrees around the pill plotted on the conventional x-axis and distancedown the intestine plotted on the conventional y-axis. This data formatmay be presented on a single page so that the entire intestine can beobserved quickly as a full page thumbnail. From this view, a mouse maybe used to zoom in on areas of interest (e.g., from operator observationor selection of areas of interest can be computer-assisted). Higherresolution data may be zoomed in for regions of interest. In theseregions, three dimensional enhancement that may be viewed in a fly-overmode employs a similar effectiveness to fly-over map controls. Locationinformation can be presented in combination with selection of areas ofinterest. These and many other data presentation modes are an outcome ofimage scanning, as opposed to conventional movie picture imaging.Post-processing may be employed to render this data into a moreconventional format of looking down the intestine so that normal dataoutput is available.

To limit the data for lower resolution pictures and to increase thelight sensitivity, groups of pixels may be combined in the lowresolution mode. This pixel combination can be performed on the array orduring processing external to the array. For instance, groups of four ormore neighboring pixels may be combined. Similarly, image datacompression may be performed by examining the neighboring pixelselectronically. In a specific example not meant to limit the presentinvention, a low resolution 320×320=100 k pixel frame may become a640×640=400 k pixel frame with a 4× magnified image resolution. In thisexample, a 16× image magnification is 1280×1280=1.6M pixel frame.Further according to this example, a 64× magnification renders2560×2560=6.5M pixel resolution. Due to the image scanning technologydescribed above, the data out before data compression is aboutone-fourth that of a conventional imager. The excessively high amount ofdata output for a full scan in the highest resolution mode may belimited by smart sensor technology in the capsule electronic controls.

In an embodiment of the present invention, electrical potentials relatedto peristalsis may be sensed differentially from electrodes near eitherend of the capsule. These electrodes may also be used to load data,electronically test, sense ingestion, and turn the capsule off or onindependently. Additionally, as will be described further below,intestinal pressure waveform data can be used to determine movement ofthe capsule. In this manner and according to a further embodiment of thepresent invention, under program control the scanner may gather a lowresolution image data during peristalsis and progress to stages ofhigher resolution scanning while the local area of the intestinal tractis quiet. The use of these high resolution modes can be used to examineparts of the intestine on the cellular level where some forms ofpre-cancer have been observed.

In an embodiment, after these engineering features are implemented onthe SOI CMOS semiconductor chip, completed wafers may be fabricated onthe semiconductor processing line. As an additional final manufacturingstep, the substrate on which the SOI wafer is constructed may be removeddown to the buried Oxide (BOX). In an embodiment, this yields acellophane-like semiconductor which may be “flip-chip” mounted on thefocal plane area of a PC-board or flex circuit in the capsule.

For a full spherical image scanner, both ends of the capsule may containone of these image scanners with its respective optics.

4. Arbitrary Sampling Scanner

Scanning systems such as facsimile machines have a specifically definedresolution coordinating to the data they acquire, which is typicallydefined by the spot size or pixel size of the imaging array. It ispossible to sub-sample the optical pixel to acquire higher resolution.In digital systems, this is typically done by utilizing more discretepixels than optical spots, thereby requiring a higher photodetectionresolution than optical resolution. This is a costly and inefficient useof the pixels. The desire for higher resolution images with basic systemdesigns has pushed the need for higher pixel counts for starring arrayssuch as focal plane array (FPA) CMOS or CCD imagers.

A scanner utilizing movement of the target or movement of the sensorsprovides the ability to utilize high response speeds to gain higherresolution data.

In an embodiment of the present invention, the analog response of aphotodetector can be utilized to capture image data from an opticalscanner so that the final resolution of the system is described by acombination of the optical spot size on the target surface being imagedand the amount of sub-sampling accomplished by an analog to digital(A/D) converter. Since A/D converters have the capability to sample atextremely high data rates, this allows the scanner to be arbitrary inresolution within the confines of the response speed of thephotodetector and the illumination spot size of the scanner optics. Asthe scanner's illumination spot moves across the scanning range, itsresponse can be much faster than the scanning rate. In this manner, thevalue of the signal from a high speed photodetector responds to changesin the intensity of the scanned spot as it moves within the diameter ofthe original spot. Plotting the response of the photodetector showschanges in the value of the detected signal corresponding to changes inthe surface of the object that are much smaller than the optical spotsize. This allows a high speed A/D converter to generate severalsub-samples of the image before the spot has moved to cover a completelynew surface area adjacent to the initial image spot. This sub-samplingability allows higher resolution details in the object to be detectedand imaged. Mapping of the changes in the sub-sampling data allowscalculations of the position, size, and intensity of surface featuressignificantly smaller than the optical spot size.

5. Video or Scanned Image Audio Content Indicator

Humans observing continuous visual data become numb to sudden,short-lived, or unexpected changes in the image. This psycho-physicalreaction is part of the human eye-brain response and is a known issuewith monitoring security cameras as well as reviewing continuous streamsof data from instruments such as medical monitoring equipment.

Because of this, reviewing long data streams of video images fromoptical scanning systems for medical applications is difficult,particularly when a majority of the scans have very similar data showingnormal tissue, while a small selection of scans may have indications ofdisease or other medical issues of key interest.

In cases where video or scanned image streams have a majority of similarcontent and human monitoring or reviewing is tedious, auditory signalsmay be used as indicators of sudden change in the image content. Forexample, some modern security systems utilize temporal differencefiltering of images to set off alarms when there are sudden changes inthe scene so as to alert security guards of possible intrusions.Similarly, medical image data can be processed to generate cues to alerta physician or observer when the scans show tissue abnormalities.

In an embodiment of the present invention, the overall intensity profileof each line or frame may be determined by utilizing the intensity ofeach of the color channels of the scanner. When objects within the imagechange the parameters of these levels, the change in intensity valuesmay exceed the normal range for the data stream. This intensity leveldata may be assigned an acoustic tone value which may be for the sum ofthe color values. In an embodiment, a tone may be assigned for eachcolor channel being imaged to generate a set of tones. When multipletones are used, a chord may be established to indicate data that iswithin a normal specification range, while data that exceeds the normalrange may be assigned tone values to generate discordant tones whoseassignments may be made to indicate the amount that the data exceeds thenormal data range. Tone intensities may also be used to indicate opticalchannel intensities, range values outside of the normal data range, orthe percentage of a frame and/or region where values exceed the normal.User selection may be made to eliminate the tones indicating normalvalues so that data exceeding the normal data range will generate alerttones. In addition, solid tones may be replaced with specific types ofmusic or other acoustic media where subtle changes in the sound obtainthe attention of the observer and alert the observer of the event in thevideo image or data.

In an embodiment, the imaging system may include a feed of the scannervideo or data stream to a computer, where the value setting of the feedis converted into audio signals via software. The value setting may thenbe passed to an audio system via cables or wireless connections. Thistype of data processing may be accomplished with, for example andwithout limitation, a microcontroller or FPGA, which may be incorporatedwith other components within the data stream handling electronics.

In the case of patient wearable systems such as wearable monitors, thistype of audio alarm may be used to notify the patient and/or physicianvia, for example, cell phone or wireless link, that the monitor hasidentified data exceeding the normal data range limits.

In this manner, the system user can be assured to be notified of thepresence of the anomaly. With individual color tone generation andanomaly size to intensity generation, unique acoustic signatures may beassociated with the nature of the anomalies, further providing thephysician or observer with acoustic diagnostic information. Tonal shiftsin the data values provides the human observer with a second sensoryinput to prevent missing important events in otherwise tedious data, andallows review of data at high speeds. Further, this acoustic assignmentprocess may be used to highlight specific images in data prior to humanreview, allowing the data stream to be filtered to show only the imageswhere the data has exceeded normal values.

6. Monitoring Peristalsis

During a peristalsis contraction, a select region of the GI tract tissueis compressed by the muscle fiber contained within its structure. Thiscompression is how the body normally moves food and waste productsthrough the GI tract. Monitoring of peristalsis or the muscle activitywith the gastric intestinal tract is critical to evaluation of thepatients ability to process and move food through the body. Damagecaused by disease, nerve damage, rupture or atrophy of the muscleslining the gastric intestinal tract (including the stomach) are causesof serious conditions that can be life threatening.

In an embodiment of the present invention, the ingestible endoscopiccapsule can utilize peristalsis, and other muscle contractions of the GItract, to provide data regarding the extent and nature of thecontraction. Additionally, the capsule may utilize the contraction tocontrol the functions of the pill such as powering up, transmittingdata, taking images, etc.

For example, pressure sensor(s) may be used within the ingestiblecapsule such that these contractions are be monitored and utilized tocontrol the timing of acoustic transmission of data and the collectionof images and other sensor data. During these contractions the tissue issqueezed against the external wall of the capsule, providing the highestacoustic coupling possible and thereby the most efficient time foracoustic signals to be sent with minimal reflections from within thegastric intestinal structure. This increase in coupling allows thecapsule to utilize minimal power for transmission as well as provide anenhancement in the ability to locate the position of the capsule, forexample, in three dimensions from acoustic detectors placed on thepatient's skin. In addition, since the capsule is not in any significantmotion between contractions the continuous collection of data such asimages between contractions generates data redundancy with little valueto the examining physician. Therefore, the pressure provided by thecontraction can also be utilized to activate the capsule's transmissionsystem and/or initiate data collection. Along with this, images of thetissue within the GI tract that is in direct contact with the surface ofthe capsule provides the ability to see the tissue with minimaldistortion, unlike when the tissue is relaxed and the distance from oneregion of the tissue is significantly different from another regionwithin the same image.

In another embodiment of the present invention, monitoring of theactivity within the gastric system is accomplished using an ingestiblecapsule sensor to detect electrical signals corresponding to muscularcontractions associated with peristalsis. Detecting electrical emissionsfrom nearby muscle activity and communicating the information via anacoustical link to sensors mounted on the skin of the patient allowsboth a detailed analysis of the peristalsis function of the gastricintestinal tract and a 3 dimensional map of the location of the pill asit collects data to be provided. This provides physicians with thelocation and extent of functional anomalies within this system.

The capsule peristalsis sensor may contain electrical field sensors suchas those used in EKG and muscle activity sensors in other biologicalmonitors. The capsule may process these electrical signals and use anonboard microcontroller to modulate a piezoelectric crystal alsocontained along with a battery power source within the capsule. Asdescribed above, the modulated acoustic signal from the capsulecontaining the electrical muscle activity data is then received byacoustic sensors contained within patches on the skin of the patient.These patches may be distributed across the body in such a manner as toprovide a three dimensional location of the pill as it is transmitting.An exemplary method and system for locating an ingestible sensor isfurther described in U.S. patent application Ser. No. 11/851,179, filedSep. 6, 2007, which is incorporated by reference herein in its entirety.Various embodiments of this sensor approach can combine other sensorsincluding imaging.

Once the location is known, scanned images may be combined with moretraditional data to provide a more detailed understanding of the scannedimages. For example, scanned images may be combined with data from atraditional magnetic resonance imaging (MRI) procedure or from atraditional ultrasound.

CONCLUSION

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. For example, the invention may take the form of acomputer program containing one or more sequences of machine-readableinstructions describing a method as disclosed above, or a data storagemedium (e.g., semiconductor memory, magnetic or optical disk) havingsuch a computer program stored therein.

The descriptions above are intended to be illustrative, not limiting.Thus, it will be apparent to one skilled in the art that modificationsmay be made to the invention as described without departing from thescope of the claims set out below. It is to be appreciated that theDetailed Description section, and not the Summary and Abstract sections,is intended to be used to interpret the claims. The Summary and Abstractsections may set forth one or more but not all exemplary embodiments ofthe present invention as contemplated by the inventor(s), and thus, arenot intended to limit the present invention and the appended claims inany way.

Embodiments of the present invention have been described above with theaid of functional building blocks illustrating the implementation ofspecified functions and relationships thereof. The boundaries of thesefunctional building blocks have been arbitrarily defined herein for theconvenience of the description. Alternate boundaries can be defined solong as the specified functions and relationships thereof areappropriately performed.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingknowledge within the skill of the art, readily modify and/or adapt forvarious applications such specific embodiments, without undueexperimentation, without departing from the general concept of thepresent invention. Therefore, such adaptations and modifications areintended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the teaching and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the teachings andguidance.

The breadth and scope of the present invention should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.

What is claimed is:
 1. An ingestible scanning device, comprising: aningestible capsule housing having a transparent window; a photo-sensingarray located within the capsule housing; a mirror located within thehousing and oriented to direct an image from a surface outside thetransparent window to the photo-sensing array; and a light source forilluminating the surface outside the transparent window.
 2. Theingestible scanning device of claim 1, wherein the mirror is rotatable.3. The ingestible scanning device of claim 1, wherein the mirror is acylindrically symmetrical reflective element or is an element combiningreflective and refractive surfaces.
 4. The ingestible scanning device ofclaim 1, further comprising a cylindrical lens between the photo-sensingarray and the mirror, the cylindrical lens being oriented to directlight from the mirror onto the photo-sensing array.
 5. The ingestiblescanning device of claim 1, further comprising a toroidal lens locatedaround the photo-sensing array, the toroidal lens oriented to directlight from the light source onto the mirror.
 6. The ingestible scanningdevice of claim 1, wherein the light source is located within thecapsule housing.
 7. The ingestible scanning device of claim 1, whereinthe light source is attached to an outer surface of the capsule housing.8. The ingestible scanning device of claim 1, wherein the light sourceis a light emitting diode.
 9. The ingestible scanning device of claim 1,wherein the light source is a light distribution ring.